Circuit arrangement for controlling cathode-ray tubes for the display of alpha-numerical characters

ABSTRACT

The specification discloses a device for generating characters on a raster type display wherein line and column signals from the display are converted into a plurality of sequential pulses on separate lines corresponding to the points of a matrix to be displayed. These generated signals are then converted into group signals corresponding to portions of different characters having a common shape. The group signals corresponding to portions of characters are combined to form entire characters and under the control of stored character information selected for display.

United States Patent Nussbaum Oct. 3, 1972 [72] Inventor: Hans-Georg Nussbaum, Bismarckstrasse 44, 28 Bremen, Germany [22] Filed: June 10, 1970 [21] Appl. No.: 45,180

[30] Foreign Application Priority Data June 25, 1969 Germany ..P 19 32 113.2

- [52] US. Cl. ..340/324 A, 178/30 [51] Int. Cl ...G06f 3/14 [58] Field of Search.....340/324 A, 166, 336; 178/15,

[56] References Cited UNITED STATES PATENTS 3,426,344 2/1969 Clark ..340/3g4 A 3,444,319 5/1969 Artzt et a1 ..340/324 A Kronenberg et al. ..340/324 A Douglas et al. ..340/324 A Primary Examiner-John W. Caldwell Assistant Examiner-Marshall M. Curtis Attorney-Frank R. Trifari [57] ABSTRACT The specification discloses a device for generating characters on a raster type display wherein line and column signals from the display are converted into a plurality of sequential pulses on separate'lines corresponding to the points of a matrix to be displayed. These generated signals are then converted into group signals corresponding to portions of different characters having a common shape. The group signals corresponding to portions of characters are combined to form entire characters and under the control of stored character information selected for display.

1 Claim, 5 Drawing Figures [COLUMN cO-UNTER WRITING MEMBER l a;

5mm w REGISTER TIMING PULSES Sm 7 (DECODER z GRO D PULSE SHAPER i MATRIX Z1 U11 J gm '2 .ERM. i a ZM I. Q L4 Zn I CHARACTER LINE Umn SELECTION COUNTER DOT MATRIX STAGE ZWST CHARACTER MATRIX (INTER SPACE CONTROL) PATENTEDUUB I972 3.696.387

SHEET 1 BF 2 T1 T2 T3 COLUMN COUNTER LINE COUNTER h h m BRIGHTNESS E MODULATION D SIGNAL T FLlP-FLOP INVENTOR. HANS GEORG NUSSBAUM 1/ 'wgfi 't PATENTEDUCT 3 I972 SHEET 2 IF 2.

m m P m R M E E W H m E S F M R L I E R U G T E P T W B D R, ,S n m w o W 2 E0 E TIE T E m S UM C L R D M Z M T M ALS A Hi H 1|: C \\C M 2 m -i M PM U D UR O OT m GM m N 1 M S 1 U T! m U U v E m S m C R n T /,Z W \lA S .1 M "S D.. T O D S .I n E 2 U Q w I I T I m s 2 Z TIWTT||1 Z Z W m M T H mN m C MATRIX (INTER SPACE CONTROL) F I g 2 INVERTER OR- GATE L CHARACTER SELECTION CHARACTER MATRIX GROUP MATRIX STAGE INVENTOR. HANS GEORG NUSSBAUM GENT CIRCUIT ARRANGEMENT FOR CONTROLLING CATIIODE-RAY TUBES FOR THE DISPLAY OF ALPHA-NUMERICAL CHARACTERS The invention relates to a circuit arrangement for controlling the electron beam intensity in the display of characters composed of matrix type elements on the screen of a cathode-ray tube with the aid of a line counter and a column counter, in which a dot matrix produces for each dot of the character field at a respective output a signal from the output signals of the line counter and the column counter.

If it is desired to extend the range of use of electronic data processing systems there is a need for simplification of the information exchange between man and machine in a sense such that not particularly skilled persons can also handle the write and read apparatus. A direct information exchange in the form of a dialogue is particularly desirable without long delay times between question and answer. For this purpose it is necessary to convert the information supplied in coded form by the computer into a legible text. Apart from the conventional apparatus e.g. the electrical typewriter or the high-speed printer the phosphor screen of a cathode-ray tube may be employed for the display of alphanumeric character. For this purpose such display screen apparatus have to include a character store in which the character to be displayed are stored in their known form.

Various possibilities of solving this storing problem are known and have been carried into effect; for example the monoscope in which the form of the sign is scanned from a given picture array inside the cathoderay tube and the charactron in which a metal mask controls the electron beam in the display tube in accordance with the form of the sign. Moreover, magnetcore, resistor and diode matrices have been employed for storing the forms of the signs. Said methods have various disadvantages. The arrangement may either be very complicated or because of an excessively long access time to the stored characters, it is capable of dis playing only a few characters on the screen. In addition the possibilities of modifying the contents of the store for different forms of character and different stocks of character may be slight. Analogue circuit arrangements are frequently employed, which in most cases require manual control of components and which inhibit the use of digital circuit elements in the integrated form.

The present invention avoids said disadvantages and is characterized in that a group matrix combines these outputs in accordance with the form of character elements preferably common to at least two of the characters to be displayed and in that a character matrix produced the complete signal of a character at a respective output of the character matrix from the resultant character elements and from the signals of the outputs of the dot matrix and, as the case be, from the direct output signals of the line counter and the column counter and in that in accordance with the character to be displayed the corresponding output of the character matrix can be selected. I

It is thus possible with the aid of comparatively little equipment to store the various forms of characters, to attain high writing speeds by short access times and, by simple changes of the circuit arrangement, to modify the contents of the store with respect to the stock of characters and the forms of characters. These properties are obtained exclusively by using digital circuits, which facilitate the use of integrated elements, whilst future techniques of highly integrated circuits may become feasible.

The circuit arrangement according to the invention is suitable for all methods in which the characters to be displayed are formed from a matrix of dots. The size of the dot matrix as well as the sequence of scanning of the matrix columns and matrix lines is arbitrary. The character may therefore be scanned and built up column by column or line by line. In a preferred embodiment, however, the store is scanned so that its output signal represents the frame signal of a television signal. If this frame signal is combined with a standard synchronizing and deflection signals, a complete television signal is obtained, which can be converted by any standard monitor into a legible text. In this method special deflection circuits may be omitted. The store output signal may also be mixed with any frame signal of a corresponding standard. Thus, for example, in picture transmissions alphanumeric characters or symbols may be introduced under computer control. This may be important in the synchronization of foreign language films or in the recording of weather graphs. It is furthermore possible to control projection television systems (for example eidophores) by this signal.

The drawing shows one embodiment of the invention, therein:

FIG. 1 illustrates the decomposition of the letter D I into elements;

FIG. 2 is a block diagram of the circuit arrangement;

FIG. 3 shows in detail the dot matrix array of FIG. 2;

FIG. 4 shows further details of the character generator of FIG. 2 (example of the production of the signs I, O and H);

FIG. 5 shows the pulse shaper IF.

FIG. 1 shows the sign D" of the form obtained by an array of dots of the size of 5 columns X 7 lines 35 dots. The beam deflection may be that of television methods. For producing this sign on the display screen the intensity of the electron beam has to be controlled so that only the dots to be displayed are scanned in order of succession. The pulse width of a sign may be I ,usec, the space interval between two signs may be 0.2 p.sec so that on one line about 43 signs are represented since the duration of one line in the CCIR-625-Iine standard amounts to 64 usec, about 18 percent of which is taken by the line fly-back blanking. Since in interlaced scanning the frame frequency is 50 Hz and since the two frames can be formed identically, the pulse sequence has to be repeated every 20 msec for intensity control.

For characters of more complicated form it is convenient to use different forms of frames in order to achieve an improved resolution. For this purpose it is not necessary to use a complete second character store as in the case, for example, of diode matrices for displaying the form of the sign; the double implementation is only required for complicated signs or parts of signs, in which case the character store is frame-controlled. It is then efficient to shift the matrix of the second frame relatively to that of the first frame.

In the method of producing a sign separate dots of the dot matrix are combined in groups so that the latter form character parts which are common to a plurality of characters. These parts are combined to form the characters. FIG. 1 illustrates this method for the D. It will be apparent that the D comprises three character parts T T T which are also found in other characters. The sign part T is, for example, also found in the letters B, E, F,-I-I etc.; the sign part T is found in the letters B, C, G etc.; and the sign. part T is found in the letters 0, 0, etc.

FIG. 2 shows the block diagram of a circuit arrangement. The essential parts here are the dot matrix PRM, the group matrix GM, the character matrix ZM and the character selection stage ZS. The arrangement operatesas follows:

The. dot matrix PRM controlled by the column counter 82 and the line counter ZZ produces in order of succession all dots of the dot matrix required for composing the various characters, the order being determined by the timing pulses Ts and T2, the number of dots in the matrix corresponding with the number of output conductors of the dot matrix PRM, which is at the most equal to the product of line and column numbers. They control the group and character matrices so that in the group matrix GM the matrix dots are combined into dot groups and in the character matrix ZM dots and dotgroups are combined to characters so that at the same time all characters stored are produced. In the character selection stage ZS only the character stored by the character writing member ZE in a given coded form in the register R and decoded by the decoder D is selected and applied as an intensity modulation signal via an or-gate O, a pulse shaper IF and an inverter I and displayed on the screen, the space control ZWST controlling blanking between thev signs and the lines.

In accordance with the above example the timing pulse Ts has a period: of 0.2 psec and determines the width of a column of the dot matrix, whereas that of the timing pulse Tz is 64 usec, determining the television line frequency of 15.625 kHz in the CCIR-625line standard.

The formation of the total television picture starts after the fly-back of the beam and after the termination of blanking at the upper left hand corner. The line counter 22 is adjusted to the first matrix line, the column counter SZ to the first matrix column. The timing pulse Ts steps on the column counter SZ and the dot matrix PRM produces in order of succession all points of the first matrix line. The television line synchronizing pulse steps on the line counter ZZ so that at the termination of the first television line the nextfollowing line is produced dot-sequentially.'

The dot matrix is shown in detail in FIG. 3. It is formed by a group of m X n and-gates in m columns (in this case 5) and n lines (in this case 7). During the production of the first line, the line counter output Z 1 has the 1 -signal and the timing pulses Ts appear sequentially at S 1, S 2 etc. up to Sm (in this case S 5). Consequently, in order of succession the outputs of the and-gates U 11, U 12 to U 1m (in this case U 15) have a 1 -signal. In the same manner during the timing pulse T2 the line counter ZZproduces in order of succession at the conductors Z! to Zn.(in this case Z 7) a 1"- signal. Thus the matrix dots of the 2nd, 3rd to nth (here 7th) line are produced by the and-gates U 21, U 2m (here U 25), U 31 U 3m (here U 35) and U n1 Unm (hereU7l-U75). I

In the or-gates of the group GM of FIG. 4, controlled by the dot 'matrix PRM the dots are assembled to dot groups so that character portions are produced, which are common to two or more characters.

By means of these dot groups, separate dots of PRM andhorizontal or vertical straight'lines formed by the direct outputs of the line counter ZZ or the column counter SZ, the separate characters are formed in the character matrix ZM by the associated or-gates, while the interspace control ZWST provides blanking of the horizontal and vertical straight lines between the characters and between the lines respectively.

The characters written in, coded form are intermediately stored in the store R in a fixed order of succession in which they have to appear on the display screen and passed through the decoder D. Thus the character selection stage ZS is controlled. In the character matrix ZM all characters are thus simultaneously produced for each place on the display screen; in the selection stage ZS, however, only that character is selected which has to be displayed in accordance with the information stored in the store R. The output conductors of the character selection stage are combined by an or-gate.

As is shown in FIG. 2 the frame signal passes through a pulse shaping stage IF, one embodiment of which is shown in detail in FIG. 5. It comprises two parts which may be included either separately or in common. The D-flip-flop of the first stage serves for compensating the transit time differences between the pulse sequences of the dot matrix PRM or the column counter SZ respectively and the pulse sequences of the group matrix GM occurring in the subassemblies due to time lags. The transit time difference At is due to the fact that the circuit producing the horizontal dash comprises more switching stages and therefore exhibits a longer pulse delay time than that producing the vertical dash. Therefore the signal for the first dot has already terminated before the signal for the next dots of the horizontal row starts and the composite signal exhibits a short 0-signal between the l-signals of the first and second columns. This interval has a disturbing effect on the display screen. In order to avoid the same the frame signal is applied to the D-input of a D-flipflop which is controlled by the timing pulse Ts of the column counter so that the transit time difference is compensated for. The second part (IB) of the pulse shaping stage IF produces a widening of the pulses. This may be necessary if it is desired to display a large number of characters on each line. In this case the fundamental frequency of a 0 l 0 l O- pulse sequence attains the magnitude of the upper limit frequency of the conventional television monitors. As a result separate dots are displayed with lower brightness than horizontal straight lines, since the duration of one dot is too short for attaining maximum brightness. The pulse widening stage comprising the inverters A, B and C in FIG. 8 produces from the given television signal a signal having widened l pulses by utilizing the signal delay time of the real digital circuits. It is supposed here that all members have the same pulse delay time At. This provides a pulse widening by 2 At- Between points A and Q (FIG. 5) any odd number, of inverters may be included in order to obtain larger pulse widening.

The inverter I inverts the output signal. The text may optionally be displayed bright on a dark background or conversely; for example, a given text written manually white on black and a text supplied by a computer may be written black on white in depence upon the control signal St. At B the brightness modulation signal (B- Signal) can be derived, which subsequent to mixing with'an identifying signal and a synchronizing signal represents the complete television signal in the CCIR- standard. This signal may control a standard television monitor.

What is claimed is:

l. A circuit arrangement for modulating a television type display with character information in the form of a dot matrix, comprising a column counter connected to receive a continuous series of pulses corresponding to the dots of the matrix on the display and providing sequential column signals on a plurality of output conductors corresponding to the number of columns in the display matrix, a line counter connected to receive a continuous series of pulses corresponding to the lines of the matrix on the display and providing sequential line signals on a plurality of output conductors corresponding to the number of lines in the matrix on the display, a dot matrix generator connected to the output conductors of the line counter and the column counter for providing a plurality of sequential pulses on separate lines each line corresponding to a dot on the matrix to be displayed, a group matrix connected to the dot matrix generator for providing on a plurality of output conductors signals corresponding to character elements common to at least two of the characters to be displayed, a character matrix connected to the output conductors of the column counter, the line counter, and the group matrix for providing on output conductors signals corresponding to all of the characters capable of being displayed on the television type display, means for storing a sequence of characters to be displayed, and a selection matrix connected to the storage means and to the character matrix for selecting the character matrix output signals corresponding to the stored characters. 

1. A circuit arrangement for modulating a television type display with character information in the form of a dot matrix, comprising a column counter connected to Receive a continuous series of pulses corresponding to the dots of the matrix on the display and providing sequential column signals on a plurality of output conductors corresponding to the number of columns in the display matrix, a line counter connected to receive a continuous series of pulses corresponding to the lines of the matrix on the display and providing sequential line signals on a plurality of output conductors corresponding to the number of lines in the matrix on the display, a dot matrix generator connected to the output conductors of the line counter and the column counter for providing a plurality of sequential pulses on separate lines each line corresponding to a dot on the matrix to be displayed, a group matrix connected to the dot matrix generator for providing on a plurality of output conductors signals corresponding to character elements common to at least two of the characters to be displayed, a character matrix connected to the output conductors of the column counter, the line counter, and the group matrix for providing on output conductors signals corresponding to all of the characters capable of being displayed on the television type display, means for storing a sequence of characters to be displayed, and a selection matrix connected to the storage means and to the character matrix for selecting the character matrix output signals corresponding to the stored characters. 